1. DESIGN AND PERFORMANCE EVALUATION OF AN EVAPORATIVE HEAT EXCHANGER A.O. MURITALA, S.O. OBAYOPO, S.K. FASHOGBON, O.T. POPOOLA*, S.A ADIO Department of Mechanical Engineering, Obafemi Awolowo University, Ile-Ife, Nigeria. International Conference on Innovations in Engineering and Technology (IET 2011) UNIVERSITY OF LAGOS, FACAULTY OF ENGINEERING, AKOKA, LAGOS, Nigeria

2. INTRODUCTION

3. Evaporative Cooling The increased air filtration qualities Simplified operation and maintenance Lower costs Lower energy usage Less greenhouse gas No CFC's or HFC's

4. Evaporative Cooler Cabinet Reservoir Tank Pad Blower Electric Motor Pump Fig 1: Schematic diagram of an evaporative cooler

5. Objective To design and construct an evaporative cooler. To evaluate the performance of the cooler.

6. DESIGN

7. General Reduction in the discomfort index by 90% Required fan power is linearly dependent on the floor area to be cooled. Building heat balance (EC sizing) SOLAR HEAT + HEAT FROM EQUIPMENT & PEOPLE = HEAT REMOVED BY EAC

8. Cabinet Reservoir Tank Galvanized iron sheet 50x55x70 cm 3 One sided Cabinet Reservoir Tank Inlet Outlet (50 x 55 x 23) cm 3

9. Evaporative Pads Aluminum fins 35 x 47 x 10 cm 3 Blower

10. Electric Motor half-horse power connected by a direct drive 2 speed motor 220 V Pump re-circulating surface pump 0.5 horse power Water pump screen

11. Plate 1: The evaporative cooler housing cabinet Plate 2: The designed evaporative cooler

12. EVALUATION

13. Monitored Parameter Room size 305 x 254 x 203 cm³ Outside air temperature Evaporative cooler inlet air temperature and humidity Evaporative cooler outlet air temperatures and humidity Water temperature in the evaporative cooler reservoir Evaporative pad surface temperature Air speeds & mass flow rate

14. RESULTS Inlet db temp (°C) Inlet HR (kg/kg) Outlet db temp (°C) Outlet HR (kg/kg) Humidity gain(kg/kg) Inlet wb temp (°C) Reservoir water temp(°C ) 133.00.013626.00.01660.003023.022.070.0 234.00.013226.00.01660.003423.022.072.7 336.00.012426.00.01660.004223.022.076.9 437.00.012026.00.01660.004623.022.078.6 538.00.012426.50.01720.004823.522.079.3 639.00.012626.50.01800.005424.022.083.3 Table 1: Dry and Wet Bulb Temperature, Humidity Ratio humidity gain and Saturation Effectiveness

15. Saturation Effectiveness & External Dry-Bulb Temperature increase in saturation effectiveness as the external db temp increases evaporative cooler is more efficient at higher outside air db temp

16. Saturation Effectiveness & Humidity Gain The saturation effectiveness increased as the humidity gain increases

17. Humidity Gain & External Dry Bulb Temperature increased gain in humidity ratio at higher external db temp Fig 4.3: Humidity gain as a function of external dry bulb temperature

18. Speed (m/s) db Temp ( 0 C) 10.7536.079.0 20.8536.077.0 Water flow rate Air Flow rate(m 3 /s) LOW 0.045 76.0 MEDIUM 0.045 75.3 HIGH 0.045 74.2

19. CONCLUSION The saturation effectiveness of pad determined from the experimental result falls between the ranges of 70-83.3%. the pad employed for the construction of the cooler is efficient and reliable. The designed evaporative coolers can maintain cooled spaces at temperatures below ambient air temperatures. The performances of the evaporative cooler were significantly affected by weather conditions. The overall cooled room temperature depression from ambient air temperature reached up to 11 0 C, and ambient air temperatures varied between 22–33 0 C.

20. Thank You !!!!